The immune system is better @ 40 ng level of Vitamin D
Serum 25(OH)D concentrations are differentially associated with innate and adaptive immune cell markers, with threshold effects near 40 ng/mL: A cross-sectional study
Nutr Res. 2026 Aug 5:154:32-45. doi: 10.1016/j.nutres.2026.08.001. PDF behind paywall
Peng Lei 1, Shaoyan Wu 1, Rong Luo 1, Binyang Tang 1, Sicen Wu 2
The nonlinear relationship and threshold effects of vitamin D on immune function in healthy adults remain unclear. This cross-sectional study of 316 healthy adults (January 2022 to June 2023) investigated associations between serum 25-hydroxyvitamin D (25(OH)D) concentrations and peripheral blood immune parameters (CD3+ T lymphocytes, CD4+ T cells, CD19+ B cells, and natural killer [NK] cells) quantified by flow cytometry. Restricted cubic spline and piecewise regression models evaluated nonlinear relationships and inflection points. Compared to the low 25(OH)D group (<28.45 ng/mL), the high group (>28.45 ng/mL) had higher NK cell counts (306.00 vs 272.50, P < .01) and percentages (15.52% vs 14.21%, P < .01), but lower CD3+ T cell percentage (69.99% vs 73.20%, P < .01). Multivariate regression confirmed that 25(OH)D was negatively associated with CD3+ T cell percentage (β = -0.16, P < .001), and positively with NK cell count (β = 3.62, P = .002) and NK cell percentage (β = 0.16, P < .001). Restricted cubic spline analyses revealed significant threshold effects, with inflection points at 40.94 ng/mL for CD3+ T cell percentage (P = .003), 37.86 ng/mL for NK cell count (P = .005), and 40.94 ng/mL for NK cell percentage (P = .022). Subgroup analyses showed stronger correlations in males and individuals 40 to 59 years of age (P < .05). Our findings suggest that vitamin D may exert threshold-dependent dual immunomodulatory effects-enhancing innate immunity (NK cells) while suppressing adaptive immune activation (CD3+ T cells). Higher 25(OH)D concentrations (around 40 ng/mL) were associated with distinct immune profiles in this healthy cohort. These associations may provide preliminary insights for future studies, although causal relationships cannot be inferred from this cross-sectional design.
Conclusion: clipped from web (>40 ng increases innate and decreases adaptive)
In summary, the present study demonstrates differential associations between 25(OH)D concentrations and innate (NK cells) vs adaptive (CD3+ T lymphocytes) immune markers, with threshold effects identified near 40 ng/mL. These cross-sectional findings suggest that higher VitD concentrations above this level were associated with enhanced innate immunity and reduced adaptive immune activation. Nevertheless, it is not possible to establish causal relationships. Future research may benefit from . . . .
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40 ng of Vitamin D
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>40 ng of vitamin D
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